Or so Elizabeth Banks had been told as a child. So she couldn't quite figure out the violent act that was happening before her very eyes in the yard of her family's Western Massachusetts home to the family's Labrador, Yankee.

It is a moment, the 34-year-old actress says, that is "now seared onto my brain. A giant German shepherd came into the yard and f---ed her right in front of me. I thought she was being killed. I was like, 'Dad! She's getting hurt!'" Up to that point, at age 12, she explains, "I thought that was what people do when they are in looove: They lie together in a bed and have sex. And not some from-behind, doggy-style thing."

To risk stating the obvious: Elizabeth Banks has an ample sense of humor about sexuality. Or, as she puts it over breakfast in a Los Angeles café, stabbing a toast point into a soft-boiled egg as if to illustrate her point: "Sex is always funny. I don't find it sexy--I find it really horrifying. But it's an act that we need. And that need, that desire, is what makes it really funny." As examples, she points to essentially the entire male population: "Every dude is trying to get laid, 24/7, from the time they're 11 or 12," she says. "Everything they do is about trying to get laid, yet they're maybe way too hairy, they fart, they have tempers. They don't know what the real situation is, and it's that struggle that I find really funny. Every man wins the lottery when he gets a woman to love him."

This month Banks can be seen in two very different movies portraying a loving woman to two such lottery winners. In Oliver Stone's W., she's Laura Bush to Josh Brolin's George; in Kevin Smith's Zack and Miri Make a Porno, she's Miri opposite Seth Rogen's Zack. As disparate as the roles sound, she played them both as love stories. "When Josh and I started talking about our characters, I was like, 'From everything I read and see about them, I think they're really in love,'" she says. "They're devoted, and that's something I understood and could play."

She could understand that kind of commitment because she's been with the same guy, Max Handelman, since she was a freshman at the University of Pennsylvania (from which she graduated magna cum laude). As of this fall, she and Handelman have been together 16 years--which, in Hollywood time, is roughly equivalent to having been together since the Mesozoic Era. They married in 2003--before he switched from a career in finance to producing movies but after she had vaulted from commercials and small TV roles to Hollywood blockbusters like Seabiscuit (she played horse-owner Jeff Bridges's wife, Marcela Howard) and Spider-Man (as Betty Brant, the long-suffering secretary of a newspaper tycoon). So what's it like having your girlfriend--the cute girl in the Red Sox hat across the quad--suddenly become this hottie on the big screen, let's say, masturbating with a detachable shower head in The 40-Year-Old Virgin? "He knows the truth. Sometimes I'm sexy, and sometimes I'm not," she says, laughing. "I don't think I'm that special, and he definitely doesn't think I am. Because no one is that special. I'm not curing cancer; I'm not saving lives. I play make-believe for a living, so let's not take it too seriously."